Micro-fluid ejection devices

ABSTRACT

A micro-fluid ejection head structure having multiple arrays of fluid ejection actuators. The structure includes a semiconductor substrate having a first array of fluid ejection actuators for ejecting a first fluid therefrom, and a second array of fluid ejection actuators for ejecting a second fluid therefrom. The first array of fluid ejection actuators is disposed in a first location on the substrate, and the second array of fluid ejection actuators is disposed in a second location on the substrate. A thick film layer having a thickness is attached adjacent the semiconductor substrate. The thick film layer has fluid flow channels formed therein solely for the first array of fluid ejection actuators. A nozzle plate is attached to the thick film layer opposite the semiconductor substrate. The nozzle plate has fluid flow channels formed therein for both the first array of fluid ejection actuators and the second array of fluid ejection actuators.

FIELD OF THE INVENTION

The invention relates to micro-fluid ejection devices such as ink jetprintheads and methods for making micro-fluid ejection devices havingimproved fluid flow characteristics.

BACKGROUND

A conventional micro-fluid ejection device such as an ink jet printheadgenerally has flow features either formed in a thick film layerdeposited on a semiconductor substrate containing ink ejection devicesor flow features ablated along with nozzle holes in a polymeric nozzleplate material. The term “flow features” is used to refer to fluid flowchannels, fluid ejection chambers, and other physical features thatprovide a fluid such as ink to ejection devices on the semiconductorsubstrate. When both the nozzle holes and flow features are ablated inthe nozzle plate material, a thick film material is typically notpresent. A disadvantage of forming the flow features and nozzle holes inthe nozzle plate material is that the flow feature height and nozzlebore length are constrained by the nozzle plate material thickness. Formicro-fluid ejection heads having a separate thick film layer and nozzleplate with the flow features formed in a thick film layer, the nozzlebore length is constrained to equal to the nozzle plate materialthickness and the flow feature dimensions are determined by thethickness of the thick film layer.

With a trend toward increasing the functionality of micro-fluid ejectiondevices, it is desirable to provide fluid ejection devices on a singlesemiconductor substrate for ejecting different fluids having differentdrop masses. However, for largely disparate drop masses, the aboveconstraints make the design of a single semiconductor substrate formultiple fluids difficult. For example, smaller droplet masses may beaccommodated using flow features ablated in a nozzle plate material of aparticular thickness. However, the larger droplet masses requireadditional flow features that cannot be ablated in a nozzle platematerial suitable only for smaller drop masses. Alternatively, largerdroplet masses may be accommodated using flow features formed in a thickfilm layer with nozzles ablated in a nozzle plate. However, the combinedthickness of the thick film layer and nozzle plate degrades the ejectionefficiency of the smaller droplet masses ejected from the samesemiconductor substrate.

As the speed of micro-fluid ejection devices such as ink jet printers,increases the frequency of fluid ejection by individual ejectionactuator elements must also increase requiring more rapid refilling offluid ejection chambers. The requirement for more rapid refillingprovides an incentive to devise a novel approach to providing flowfeatures suitable for fluid ejection actuators for multiple size dropletmasses on a single semiconductor substrate. Hence, there exists a needfor improved micro-fluid ejection devices and methods for making thedevices.

SUMMARY OF THE DISCLOSURE

With regard to the foregoing, the disclosure provides an improvedmicro-fluid ejection head structure having multiple arrays of fluidejection actuators. The structure includes a semiconductor substratehaving a first array of fluid ejection actuators for ejecting a firstfluid therefrom, and a second array of fluid ejection actuators forejecting a second fluid therefrom. The first array of fluid ejectionactuators is disposed in a first location on the substrate, and thesecond array of fluid ejection actuators is disposed in a secondlocation on the substrate. A thick film layer having a thickness isattached adjacent the semiconductor substrate. The thick film layer hasfluid flow channels formed therein solely for the first array of fluidejection actuators. A nozzle plate is attached to the thick film layeropposite the semiconductor substrate. The nozzle plate having fluid flowchannels formed therein for both the first array of fluid ejectionactuators and the second array of fluid ejection actuators.

In another embodiment, there is provided a method of making amicro-fluid ejection head structure. The method includes the steps ofproviding a semiconductor substrate and forming a first array of fluidejection actuators for ejecting a first fluid therefrom in a firstlocation on the semiconductor substrate. At least a second array offluid ejection actuators for ejecting a second fluid therefrom is formedin a second location on the semiconductor substrate. A thick film layeris deposited with a thickness adjacent the first and second arrays offluid ejection actuators on the semiconductor substrate. Fluid flowchannels are formed in the thick film layer solely for the first arrayof fluid ejection actuators. A nozzle plate material is provided forattachment to the thick film layer. Fluid flow channels are formed inthe nozzle plate material for both the first and second arrays of fluidejection actuators. The nozzle plate is attached to the thick film layeropposite the semiconductor substrate to provide the micro-fluid ejectionhead structure.

An advantage of the embodiments described herein is that it enablesindependent variation of fluid flow characteristics for multiple arraysof fluid ejection actuators on a single substrate. Independent variationof fluid flow characteristics is provided by combining fluid flowchannels formed in thick film layer with fluid flow channels and nozzleholes formed in a nozzle plate material for at least one array of fluidejection actuators. As a result of embodiments, fluid ejector arrays ofdifferent ejection volumes may be included on a single ejection head.For example, an ink ejection head may include ejection actuators forblack ink that eject about four times the volume of ink ejected fromcyan, magenta, and yellow ejection actuators on the same ejection head.Another advantage is that an ejection head having two different sizeejection actuator arrays for a single fluid may be provided with asingle fluid source without deleteriously affecting the fluid flow tothe two actuator arrays. Such advantages are not easily provided byconventional ejection heads and fabrication methods.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the embodiments may be better understood byreference to the detailed description when considered in conjunctionwith the figures, which are not to scale and which are provided toillustrate the principle features described herein. In the drawings,like reference numbers indicate like elements through the several views.

FIG. 1 is a perspective view, not to scale, of a fluid cartridge andmicro-fluid ejection head according to the invention;

FIG. 2 is plan view, not to scale, of a semiconductor substratecontaining multiple arrays of fluid ejection actuators adjacent fluidsupply slots;

FIG. 3 is plan view, not to scale, of a portion of a micro-fluidejection head structure according to the disclosure;

FIGS. 4 and 5 are a cross-sectional views, not to scale, of portions ofa micro-fluid ejection head structure according to one embodiment of thedisclosure;

FIGS. 6 and 7 are perspective views, not to scale, of portion of amicro-fluid ejection head according to disclosure;

FIG. 8 is a cross-sectional view, not to scale, of a portion of fluidflow channels for a micro-fluid ejection head structure according to thedisclosure; and

FIG. 9 is a plan view, not to scale, of a portion of a thick film layercontaining fluid chambers and fluid flow channels for adjacent fluidejectors.

DETAILED DESCRIPTION OF THE EMBODIMENTS

With reference to FIG. 1, a fluid supply cartridge 10 for use with adevice such as an ink jet printer includes a micro-fluid ejection head12 fixedly attached to a fluid supply container 14, as shown in FIG. 1,or removably attached to a fluid supply container either adjacent to theejection head 12 or remote from the ejection head 12. In order tosimplify the description, reference may be made to inks and ink jetprintheads. However, the invention is adaptable to a wide variety ofmicro-fluid ejecting devices other than for use in ink jet printers andthus is not intended to be limited to ink jet printers.

The ejection head 12 preferably contains a nozzle plate 16 containing aplurality of nozzle holes 18 each of which are in fluid flowcommunication with a fluid in the supply container 14. The nozzle plate16 is preferably made of an ink resistant, durable material such aspolyimide and is attached to a semiconductor substrate 20 that containsfluid ejection actuators as described in more detail below. Thesemiconductor substrate 20 is preferably a silicon semiconductorsubstrate.

Fluid ejection actuators on the semiconductor substrate 20 are activatedby providing an electrical signal from a controller to the ejection head12. The controller is preferably provided in a device to which thesupply container 14 is attached, such as an ink jet printer. Thesemiconductor substrate 20 is electrically coupled to a flexible circuitor TAB circuit 22 using a TAB bonder or wires to connect electricaltraces 24 on the flexible or TAB circuit 22 with connection pads on thesemiconductor substrate 20. Contact pads 26 on the flexible circuit orTAB circuit 22 provide electrical connection to the controller in theprinter for activating the fluid ejection actuators on the ejection head12.

During a fluid ejection operation such as printing with an ink, anelectrical impulse is provided from the controller to activate one ormore of the fluid ejection actuators on the ejection head 12 therebyforcing fluid through the nozzles holes 18 toward a media. Fluid iscaused to refill ink chambers in the ejection head 12 by capillaryaction between actuator activation. The fluid flows from a fluid supplyin container 14 to the ejection head 12.

It will be appreciated that micro-fluid ejection devices such as ink jetprinters continue to be improved to provide higher quality images. Suchimprovements include increasing the number of nozzle holes 18 andejection actuators on a semiconductor substrate 20, reducing the size ofthe nozzle holes 18 and substrate 20, and increasing the frequency ofoperation of the ejection actuators.

One improvement includes providing an ejection head capable of ejectingmultiple different fluids. Such an ejection head is provided by asubstrate 28 containing multiple fluid supply slots 30, 32, 34, and 36(FIG. 2) and corresponding arrays 38, 40, 42, 44, and 46 of fluidejection actuators 47. An “array” of fluid ejection actuators is definedas a substantially linear plurality of actuators 47 adjacent one or bothsides of a fluid supply slot 30, 32, 34, or 36.

The frequency of fluid ejection from each of the arrays 38–46 depends onfluid flow characteristics of an ejection head containing the substrate28. For example, the operational frequency of fluid ejection from eachnozzle in a nozzle plate is limited by the time required to replenishfluid to a fluid chamber adjacent the fluid actuator 47. Fluid refilltimes are affected by the flow feature dimensions of the ejection head.

A portion of an ejection head 48 containing the substrate 28 and anozzle plate 50 is illustrated in FIG. 3. As will be appreciated fromFIG. 3, each array 38, 40, and 42 of fluid ejection actuators 47contains a staggered array of actuators 47. Accordingly, adjacent fluidchambers, such as chambers 52 and 54 are disposed a different distancefrom the fluid supply slot 30. Accordingly, the length of fluid supplychannels 59 and 61 for adjacent fluid chambers 52 and 54 is differentthereby resulting in different fluid flow characteristics to thechambers 52 and 54. The distance D between a fluid supply slot edge 56and an entrance 58 to the fluid flow channel 59 is referred to herein asthe “shelf length.” (FIGS. 3 and 6).

A cross-sectional view, not to scale, of a portion of the ejection head48 is illustrated in FIG. 4. The ejection head 48 includes thesemiconductor substrate 28 containing fluid ejection actuators 47disposed thereon. For simplicity, the fluid ejection actuators 47, asdescribed herein, are thermal fluid ejection actuators. However, theembodiments of the disclosure are applicable to other types of fluidejection actuators, including but not limited to, piezoelectric fluidejection actuators, electrostatic ejection actuators, and the like.

As shown in FIG. 4, a portion of the fluid flow channel 64 from thefluid supply slot 30 to a fluid chamber 66 is formed in both a thickfilm layer 68 and in the nozzle plate 50. In contrast, fluid flowchannel 70 for ejector array 42 is formed only in the nozzle plate 50 asshown in FIG. 5. Because the thick film layer 68 does not provide aportion of the fluid flow channels 70 for ejector array 42, a fluidejection actuator 47 is disposed in a recessed area 76 of the thick filmlayer 68. The recessed actuator 47 may be referred to herein as a “tubactuator” as the actuator is essentially surrounded by the thick filmlayer 68.

The flow features formed in the nozzle plate 50 may be formed as bylaser ablating the nozzle plate material. Typically, the nozzle plate 50is made of a polyimide material that is readily laser ablatable.Materials suitable for nozzle plate 56 according to the invention aregenerally available in thicknesses ranging from about 10 to about 70microns. Commercially available nozzle plate materials have thicknessesof 25.4 microns, 27.9 microns, 38.1 microns, or 63.5 microns. Of thetotal thickness of the nozzle plate material, 2.54 or 12.7 microns mayinclude an adhesive layer that is applied by the manufacturer to thenozzle plate material. It will be understood however, that the inventionis also applicable to a nozzle plate material that is provided absentthe adhesive layer. In this case, an adhesive may be applied separatelyto attach the nozzle plate 50 to the thick film layer 68.

The flow features may be formed in the thick film layer 68 as by aphotolithographic technique. Typically, the thick film layer 68 is madeof a photoresist material, either positive or negative photoresist, thatis spin coated onto the substrate 28. In FIGS. 4 and 5, a single thickfilm layer 68 is illustrated. However, the thick film layer 68 mayinclude a photoresist planarizing layer having a thickness ranging fromabout 0.5 to about 5.0 microns and a separate thick film layer having athickness ranging from about 5 to about 15 microns.

A perspective view of arrays 38 and 42 is illustrated in FIGS. 6–7. Asshown in FIG. 6, array 38 includes nozzle holes 78 that aresubstantially larger than nozzle holes 80, FIG. 7. Accordingly, arrays38 and 40 are configured for ejecting a larger volume of fluid, forexample from about 15 to about 35 nanograms of fluid, as opposed toarray 42 that is designed to eject from about 1 to about 8 nanograms offluid.

Having a single ejection head 48 containing multiple size fluid ejectionactuators 47 and nozzle holes 78 and 80 provides increased versatilityfor use of the ejection head 48. For example, a multi-color ink jetprinthead may include the ejection head 48, wherein black, cyan,magenta, and yellow inks are ejected from the ejection head 48. Each ofthe inks may have a different flow characteristic or volume requirementwhich may be achieved by variation in the fluid flow feature design ofthe ejection head 48 for each of the inks.

As will be further appreciated, providing a suitable thick film layer 68and ablatable nozzle plate 50 enables tuning fluid flow characteristicsfor more efficient fluid ejection at higher frequencies. In embodimentsdescribed herein, the flow features for the fluid ejection arrays 38–46are relatively independent of either of the thickness of the thick filmlayer 68 or of the thickness of the nozzle plate 50.

Variations in the flow feature dimensions between adjacent fluid flowchannels 59 and 61 enable tuning of fluid flow to the fluid chambers 52and 54. For example, even though fluid chamber 52 is relatively furtheraway from the fluid supply slot 30 than fluid chamber 54, refill timesfor the fluid chambers 52 and 54 can be made similar by varying certaindimensions of the fluid flow channels 59 and 61 as herein described.With reference of FIGS. 8 and 9, fluid flow channel 59 includes a chokedimension CD₁ and an inlet channel dimension CD₂. A length L₁ of thechannel 59 having choke dimension CD₁ is selected so that the fluid flowcharacteristics to chamber 52 are similar to the fluid flowcharacteristics to chamber 54. In this case, chamber 54 has fluid flowchannel 61 having a length L₂ and a choke dimension CD₃. However,channel 61 may have a choke dimension CD₃ that is the same or differentfrom choke dimension CD₁ depending on the length L₂ of the channel 61.In this case, inlet channel dimension CD₂ for channel 59 is made aslarge as possible so as to avoid restricting the flow to channel 59.

The foregoing modification of the fluid flow channel 59 is possiblebecause the fluid flow channel 59 is formed in both the thick film 68and in the nozzle plate 50. By contrast, the fluid flow channels 86 and88 for nozzle holes 80 are formed only in the nozzle plate 50. FIG. 8 isa cross-sectional view, not to scale, of a portion of the fluid flowchannels 59, 61, and 90 for fluid chambers 52, 54, and 92 (FIG. 3). Asillustrated in FIG. 8, fluid flow channels 59, 61, and 90 are formed inboth the thick film layer 68 and in the nozzle plate 50. However, fluidflow channels 59 and 90 have an increased inlet channel dimension CD₂provided in the thick film layer 68.

For further clarification, let CD₄ (FIG. 8) be the width of the ablatedregion of the fluid flow channel 59 in the nozzle plate 50. CD₂ is thewidth of the inlet channel dimension for fluid flow channel 59, CD₁ isthe width of the choke region of the fluid flow channel 59, and CD₃ isthe width of the choke region of the fluid flow channel 61 in the thickfilm layer 68. The depth or height of the ablated region of the fluidflow channels 59 and 61 in the nozzle plate 50 is HA. The thickness ofthe thick film layer is TF. The center to center spacing betweenadjacent fluid flow channels 59 and 61 is the pitch P. Accordingly, thewidth WTF of a thick film layer 68 wall remaining between fluid flowchannels 59 and 61 is defined by P−(½CD₂+½CD₃)=WTF.

To assure the most robust adhesion of the thick film layer 68 to thesubstrate 28, it is desirable to size CD₂ such that WTF is greater thanor equal to TF, where WTF is at least about 12 microns.

With regard to the above relationships, a comparison of the dimensionsfor ejector arrays 38 and 42 with reference to FIGS. 8 and 9 is providedby way of the following non-limiting example.

Dimensions (Nozzle Plate 50 Ejector Array Ejector Array and Thick filmlayer 68) 38 (microns) 42 (microns) Thick Film thickness (TF) 9 9 NozzlePlate Thickness (NP) 38.1 38.1 Nozzle Plate Ablation Depth (HA) 9 18Nozzle Bore Length 29.1 20.1 Thick Film Choke Length (L₁) 16 None ThickFilm Choke Length (L₂) 22 None Thick Film Choke Width (CD₁) 18 NoneThick Film Channel Inlet 35 None Width (CD₂) Thick Film Choke Width(CD₃) 18 None Nozzle Plate Choke Width (CD₄) 18 16 Nozzle Plate ChokeLength 22 22 (near nozzle) Nozzle Plate Choke Length 16 16 (far nozzle)Nozzle Plate Channel Inlet Width 35 35

In order to provide similar flow characteristics for chambers 52 and 54in ejector arrays 38 and 40 (FIGS. 8 and 9), the following dimensionsare provided, by way of example only and are not intended to limit theembodiments described herein in any material way.

Flow Channel Flow Channel Dimensions 59 (microns) 61 (microns) ThickFilm Thickness (TF) 9 9 Nozzle Plate Ablation Depth (HA) 9 9 Thick FilmChoke Length (L) 16 (L₁) 22 (L₂) Thick Film Choke Width (CD)  18 (CD₁) 18 (CD₃) Thick Film Channel Entrance (CD₂) 35 18 Pitch (P) 42.3  ThickFilm Wall (WTF) 15.8  Flow resistance ratio  0.998 (flow channels 61 to59)

For flow channels 59 and 61, the resistance of each channel issubstantially the same as evidenced by the flow resistance ratio ofabout 1.0. Accordingly, the ejected mass of fluid from each channel 59and 61 is approximately the same. It will be appreciated that the thickfilm layer 68 thickness (TF) may be decreased by increasing the chokewidths (CD₁ and CD₃) for the channels and/or decreasing the chokelengths (L₁ and L₂). A reduced choke length (L₁ and L₂) enables use of anarrower substrate 28, thereby reducing the cost of a substrate 28containing multiple fluid supply slots 30–36 for multiple fluids.However, the flow resistance of adjacent fluid flow channels 59 and 6 ican be made substantially the same by varying the choke widths (CD₁ andCD₃) in the thick film layer 68 to provide equivalent jettingperformance for the adjacent fluid chambers 52 and 54. Furthermore, anejection head 48 for ejecting different volumes of different fluids maybe provided using a combination of the thick film layer 68 of minimumthickness and the nozzle plate 50 wherein the fluid flow channels may bespecifically configured for each array of fluid ejection actuators38–46.

Having described various aspects and embodiments of the disclosure andseveral advantages thereof, it will be recognized by those of ordinaryskills that the embodiments described herein are susceptible to variousmodifications, substitutions and revisions within the spirit and scopeof the appended claims.

1. A micro-fluid ejection head structure comprising: a substrate havinga first array of fluid ejection actuators for ejecting a first fluidtherefrom, and a second array of fluid ejection actuators for ejecting asecond fluid therefrom; a thick film layer having a thickness attachedadjacent the substrate, the thick film layer having fluid flow channelsformed therein for all of the first array of fluid ejection actuatorsand not for any of the second array of fluid ejection actuators; and anozzle plate attached to the thick film layer opposite the substrate,the nozzle plate having fluid flow channels formed therein for both thefirst array of fluid ejection actuators and the second array of fluidejection actuators.
 2. The micro-fluid ejection head structure of claim1, further comprising a third array of fluid ejection actuators disposedin a third location on the substrate, wherein the nozzle plate has fluidflow channels formed therein for the third array of fluid ejectionactuators.
 3. The micro-fluid ejection head structure of claim 2,further comprising a fourth array of fluid ejection actuators disposedin a fourth location on the substrate, wherein the nozzle plate hasfluid flow channels formed therein for the fourth array of fluidejection actuators.
 4. The micro-fluid ejection head structure of claim1, wherein the fluid ejection actuators comprise thermal fluid ejectionactuators.
 5. A multi-color printhead comprising the micro-fluidejection head structure of claim
 1. 6. An ink jet printer comprising themulti-color printhead of claim
 5. 7. A micro-fluid election headstructure comprising: a semiconductor substrate having a first array offluid ejection actuators for ejecting a first fluid therefrom, the firstarray of fluid ejection actuators being disposed in a first location onthe substrate, and at least a second array of fluid ejection actuatorsfor ejecting a second fluid therefrom, the second array of fluidejection actuators being disposed in a second location on the substrate;a thick film layer having a thickness attached adjacent thesemiconductor substrate, the thick film layer having fluid flow channelsformed therein solely for the first array of fluid ejection actuators;and a nozzle plate attached to the thick film layer opposite thesemiconductor substrate, the nozzle plate having fluid flow channelsformed therein for both the first array of fluid ejection actuators andthe second array of fluid ejection actuators, wherein the fluid flowchannels include a fluid throat, wherein the fluid throat has a width inthe thick film layer that is at least as wide as a fluid throat width inthe nozzle plate.
 8. The micro-fluid ejection head structure of claim 7,further comprising a width of thick film layer between adjacent fluidthroats that is equal to or greater than the thickness of the thick filmlayer.
 9. The micro-fluid ejection head structure of claim 8, whereinthe width of thick film layer between adjacent fluid throats is at leastabout 6 microns wide.
 10. The micro-fluid ejection head structure ofclaim 8, wherein the thickness of the thick film layer ranges from about5 microns to about 15 microns.
 11. A micro-fluid ejection head structurecomprising: a substrate having a first array of fluid ejection actuatorsfor ejecting a first fluid therefrom, and a second array of fluidejection actuators for ejecting a second fluid therefrom; a thick filmlayer having a thickness attached adjacent the substrate, the thick filmlayer having fluid flow channels of a first height formed therein forthe first array of fluid ejection actuators and having fluid flowchannels of a second height formed therein for the second array of fluidejection actuators, wherein the second height is different from thefirst height; and a nozzle plate attached to the thick film layersopposite the substrate, the nozzle plate having fluid flow channelsformed therein for both the first array of fluid ejection actuators andthe second array of fluid ejection actuators.
 12. The micro-fluidejection head structure of claim 11, further comprising a third array offluid ejection actuators disposed in a third location on the substrate,wherein the nozzle plate has fluid flow channels formed therein for thethird array of fluid ejection actuators.
 13. The micro-fluid ejectionhead structure of claim 12, further comprising a fourth array of fluidejection actuators disposed in a fourth location on the substrate,wherein the nozzle plate has fluid flow channels formed therein for thefourth array of fluid ejection actuators.
 14. The micro-fluid ejectionhead structure of claim 11, wherein the second array of fluid ejectionactuators comprises ink chambers recessed in the thick film layer.
 15. Amulti-color printhead comprising the micro-fluid ejection head structureof claim
 11. 16. A micro-fluid ejection head structure comprising: asemiconductor substrate having a first array of fluid ejection actuatorsfor ejecting a first fluid therefrom, the first array of fluid ejectionactuators being disposed in a first location on the substrate, and atleast a second array of fluid ejection actuators for ejecting a secondfluid therefrom, the second array of fluid ejection actuators beingdisposed in a second location on the substrate; a thick film layerhaving a thickness attached adjacent the semiconductor substrate andfirst array of fluid ejection actuators, the thick film layer havingfluid flow channels of a first height formed therein for the first arrayof fluid ejection actuators and having fluid flow channels of a secondheight formed therein for the second array of fluid ejection actuators,wherein the second height ranges from about 0 to about the thickness ofthe thick film layer; and a nozzle plate attached to the first andsecond thick film layers opposite the semiconductor substrate, thenozzle plate having fluid flow channels formed therein for both thefirst array of fluid ejection actuators and the second array of fluidejection actuators, wherein the fluid flow channels include a fluidthroat, wherein the fluid throat has a width in the thick film layerthat is at least as wide as a fluid throat width in the nozzle plate.17. The micro-fluid ejection head structure of claim 16, furthercomprising a width of thick film layer between adjacent fluid throatsthat is equal to or greater than the thickness of the thick film layer.18. The micro-fluid ejection head structure of claim 17, wherein thewidth of thick film layer between adjacent fluid throats is at leastabout 6 microns wide.
 19. The micro-fluid ejection head structure ofclaim 17, wherein the thickness of the thick film layer ranges fromabout 5 microns to about 15 microns.